Dame Anna Wintour is stepping back as editor-in-chief of American Vogue after 37 years.

The British-born fashion magnate, 75, is leaving the role she has held longer than any other editor, but will retain senior positions at its publisher.

Dame Anna will continue as Vogue's global editorial director, as well as chief content officer for its parent company, Conde Nast.

She was made a dame by the late Queen Elizabeth II for services to fashion and journalism in 2017, and was made a Companion of Honour by King Charles earlier this year.

Dame Anna announced to staff on Thursday that a new role, head of editorial content, would be introduced at American Vogue.

According to an account published by the company, Dame Anna told staff she wanted to help "the next generation of impassioned editors storm the field with their own ideas" as she announced her departure from the editor-in-chief role.

She said she would continue with many of her responsibilities, and that "it goes without saying that I plan to remain Vogue's tennis and theatre editor in perpetuity".

Raised in London, Dame Anna was the editor of British Vogue before she took the helm at its US sister publication in 1988.

She is credited with giving American Vogue a new lease of life, turning it into one of the world's top fashion publications and was credited with overhauling its output, including featuring less well-known models and mixing inexpensive clothes with couture.

Over her long career, Dame Anna has become one of the most recognisable and influential figures in the fashion industry.

Outside of her work with Vogue, she has also organised the Met Gala, a New York fundraiser which attracts high-profile celebrities, since 1995.

She is known for her trademark bob and dark glasses. Last December, she told the BBC's culture editor Katie Razzall the signature shades were a "prop", and "they help me see and they help me not see".

Dame Anna's tenure as editor-in-chief of US Vogue is also widely rumoured to have inspired the tyrannical but revered character of Miranda Priestly in The Devil Wears Prada - a novel by a former assistant of Wintour, Lauren Weisberger.

Earlier this year, King Charles asked Dame Anna whether she would stop working, to which she said she replied "firmly no".